Filament current stabilizer



Aug. 5, 1950 E. B. GRAVES I 2,518,539

- FILAMENT CURRENT STABILIZER Filed Sept..2"l, 1944 I I0 ll l8 20 I34. z 2" mi Smmuzin. UmT. 1

INVENTOR.

Euwnao B. Gnavas and i917 is proportionate to the tube load, it fol-' lows that as the tube load increases, electrode l8 absorbs more electrons from filament II; and

as the tube load decreases, electrode 18 absorbs less electrons from filament I8. The circuits are so designed that this action of electrode 18 and its energizing circuit compensates for tube load fluctuations and so holds the tube load substantially constant.

Preferably, taps l6, l6", etc. are provided on.

.be understood that I do not desire to be limited to -the application of my invention in this single field. only. In other Words, my invention is equally applicable to X-ray tubes having other types of energizing circuits. To illustrate What I mean, myinvention may be applied to a tube having a fully rectified circuit such as shown in PatentNo. 2,189,894, granted February 13, 1940, to- Edw in R. Goldfield .et al. This Goldfield patent shows a circuit including a milliammeter 9 adapted to show the correct value of the current flowing in the X-ray tube 2. I contemplate the placingof my electrode l8 about the filament 2a of. this Goldfield device and the'placing of my transformer winding 22a in series with the milliammeter 9 of the Goldfield patent with the rest of my "control circuit for my filament 1| and electrode la the same as shown in Fig. 1 of my drawings. In other words, I wish to emphasize that the drawing is illustrative of one embodiment, and my device willoperate as disclosed providing only that the charge supplied to the electrode l8 varies proportionately to the trueload on the X-ray tube.

What I claim is: 1 -1. In a stabilizer for tube current in an X-ray tube having-a heated cathode filament, means for supplying current to said filament greater than that necessary toproduce the desired currenti-fiow in said tube, and means including a circuit responsive to every variation in current flow in -said tube at all times and including an electrode adjacent said heated cathode filament for absorbing suflicient excess electrons from said filament tohold current flow in said tube tothe desired level as said filament current fluctuates during use.

' 2. In a stabilizer for tube current in an X-ray tube having a heated cathode filament, the combination of anelectrode adjacent said filament, means including a circuit varying in direct relation to current fiowing in said tube at all times fonenergizing said electrode with a graduated charge adapted to absorb electrons from said filament, means for energizing said filament including means for selecting a desired filament current, and means acting concurrently with said current selecting means for varying said first 3. In a stabilizer for tube current in an X-ray tube having an anode and a heated cathode filament and having a circuit between said anode and cathode, the combination of an electrode adjacent said filament, a first transformer, a second circuit for energizing said electrode with a charge adapted to absorb electrons from said filament and including the secondary of said first transformer, a second transformer having one winding in said first named circuit, and a third circuit for energizing the primary of said first transformer, said third circuit including another winding of said second transformer.

4. The combination of claim 3 including variable. means for heating said cathode filament, means for varying said last named means including a selector, and means for varying the current flowing in' said third circuit operable by said selector.

5. A stabilizer for tube current in an X-ray tube having an anode and a heated cathode filament wherein said tube is energized by a high tension transformer having a secondary with a central grounded circuit, said stabilizer comprising an electrode adjacent said filament to affect electron flow therefrom, a first transformer having-a secondary in circuit with said electrode, said first transformer having a primary, stable electrical source means for energizing said primary, and a second transformer having one winding in series in said central grounded circuit, said second transformer having another winding in circuit with said primary of said first transformer.

6. The combination of claim 5 including a third transformer having a secondary in circuit with said heated cathode filament, said third transformer having a primary, electrical source means for energizing said primary, electricity flow control means for each of said electrical source means, and means for concurrently actuating said control means.

- 7. In a stabilizer for tube current in an X-ray tube having an anode and a heated cathode filament and having a power circuit between said anode and cathode filament, the combination of a stabilizing electrode adjacent said filament and positioned to affect electron fiow relative to said filament, a first transformer having a secondary in circuit with said electrode, said first transformer having a primary, first electrical source means for energizing said primary, a second actuating means operatively connected with said electricityfiow control means for concurrently actuating both of said control means at one setting, said actuating means being calibrated in terms- .of desired X-ray tube operating current,

said actuating means at a given setting selectingv avalue for'said control means for said second source means for over-exciting said cathode filament for said desired X-ray tube current, and atv the same time said actuating means selectin; a value for said control means for said first source means for opposing said amount of excitation over the value necessary to produce said desired X-ray tube current. I EDWARD B. GRAVES.

(References on following page) REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,631,626 Coolidge June 7, 1927 1,683,194 Kearsley Sept. 4, 1928 1,946,287 Kearsley Feb. 6, 1934 Number Number Name Date Kearsley Feb. 6, 1934 Atlee Feb. 1, 1944 Garretson July 30, 1946 FOREIGN PATENTS Country Date Great Britain Aug. 12, 1926 

